Defibrillation Protection Circuit for Low-Impedance Signal Sensing
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Solution Overview
Problem
Medical equipment sensing circuits are vulnerable to damage from defibrillation shocks, and existing protection circuits are inadequate for sensing signals with low impedance measurements, such as those indicative of blood clots during procedures like thrombectomy, without impacting the performance of external defibrillators.
Innovation Solution
A defibrillation protection circuit that isolates sensing electrodes from circuitry when not in use and includes relays to manage low impedance measurements, protecting the sensing circuits from electrical surges while allowing accurate signal detection during therapeutic procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a defibrillation protection circuit is activated to protect sensing circuits from defibrillation shocks, then the sensing circuits are protected from damage, but the ability to accurately sense low impedance signals is degraded
Solution Approach 1:
The protection circuit dynamically switches between protected and unprotected states based on whether the medical apparatus is delivering therapy. A switch element (relay or transistor) is controlled by a therapy delivery indicator to connect or disconnect the sensing electrodes from the sensing circuitry, allowing the circuit to adapt its protection level according to operational context
Solution Approach 2:
The protection circuit is configured to be activated before potential defibrillation shocks occur by monitoring therapy delivery status. The control system preliminarily determines when protection is needed based on therapy delivery indicators, enabling the switch to close and isolate the sensing circuitry before a defibrillation event occurs
2Measurement precision
If the sensing electrodes are continuously connected to the sensing circuitry, then low impedance signals can be accurately detected, but the sensing circuits become vulnerable to defibrillation shock damage
Solution Approach 1:
The connection state between sensing electrodes and sensing circuitry is dynamically controlled based on therapy delivery status. During therapy delivery, the switch element disconnects the sensing circuitry to protect it from defibrillation shocks. Outside of therapy delivery, the switch element connects the sensing electrodes to enable accurate low impedance signal detection
Solution Approach 2:
The harmful exposure to defibrillation shocks is extracted or removed from the sensing circuitry by using a switch element to physically disconnect the sensing circuitry from the sensing electrodes during therapy delivery, isolating the vulnerable sensing circuitry from the harmful electrical surges
3Reliability
If a protection circuit is added to protect sensing circuits, then the reliability against defibrillation shocks is improved, but the device complexity increases
Solution Approach 1:
The protection circuit functionality is merged with the existing control system of the medical apparatus. The switch element is controlled by the same control system that manages therapy delivery, combining the protection function with the existing control architecture rather than adding a completely separate control system
Solution Approach 2:
The protection circuit operates autonomously based on therapy delivery status detection. The control system automatically controls the switch element based on whether therapy is being delivered, eliminating the need for manual intervention or additional complex control logic
Data Source
AI summary
A medical apparatus includes a therapy component for performing a therapeutic procedure on the patient. The therapy component includes sensing circuitry for sensing electrical signals from one or more sensing electrodes of the therapy component that are placed on and/or in the patient. With the medical apparatus powered on, a determination is made as to when the therapy component is actively engaged in performing the therapeutic procedure on the patient. When the therapy component is actively engaged in performing the therapeutic procedure on the patient, the one or more sensing electrodes of the therapy component are electrically connected to the sensing circuitry. When the therapy component is determined to not be actively engaged in performing the therapeutic procedure on the patient, the one or more sensing electrodes of the therapy component are electrically isolated from the sensing circuitry.